[tom s]

3.55s are not very highway friendly,have had them in a lot of A bodies.3.42s are on my ragged edge.Have 3.31s in my bird.Tom

[Kevin]

I'm not set on any particular ratio, I could always sell the 3.55 and get something else. I live in a very rural area, the car will never see an interstate highway. It will be old twisty two lane roads most of the time. Right now I just want to focus on coming up with a plan to get it running and moving under it's own power again.

[phil400]

If the main focus is too just get it running Id go 068, was originally designed for high compression, works with all the stock stuff and would probably run pretty good regardless of what rear gear your runnin now or later.

And later on if want more throw some melling 1.65 rockers, adding lift and a few degrees over the nose.

[Jay S]

The 068 (SPC-7 Melling) matches the 2.93 gears and stock converter better than the bigger cams like the SPC-3 or Summit 2802, or those Crower’s. With 3.55s though for slightly more performance it would have room for more cam, or more cam and high stall converter, and 2.93s. But I would not go to a higher lift cam (.470” +) unless you put in new valves and posi seals in, and get rid of the splash guards.

There is probably only around a point of octane difference between a 068 and 744 cam. If memory serves, there is about 10lbs of pumping compression difference with the SPC-3 over the SPC-7 (lower) and slightly less difference then that with the 068 to an 2802 Summit. But it also depends on how each is installed.

[b-man]

With your current combo I’d run the 068 cam with a good set of new springs. It will run fine with the log exhaust manifolds coupled with a free flowing 2-1/2” exhaust. Make sure you use a mandrel bent set of head pipes right off the manifolds (Pypes carries these) as well as the whole exhaust.

The 2.93 gear is a good compromise between city and highway, the engineers knew what they were doing. I would plan in the future to swap to 3.23 gears if you find the 2.93 gears aren’t to your liking as they will fit on the same differential gear carrier as the 2.93s but the 3.55s won’t. Pontiac engines have the torque to successfully use highway gears so I wouldn’t be so quick to swap the 2.93s out.

Most definitely use the highest octane pump fuel you can find, having the distributor reworked to alter the timing curve might be the key to making it all come together.

Good luck with your project.

[Skip Fix]

Heck my low compression 180 HP Trans Am came factory with 2.56s!. My 81 has 3.08s and a 2801 and is a good combination.

[b-man]

A new cam and lifters along with a new timing chain set can really wake up one of these engines that have accumulated some miles. The cam usually has a couple lobes going flat and the timing chain is stretched retarding the cam timing events, not to mention valve springs that have lost their tension.

I think you’ll be surprised how well it runs after replacing these worn out components.

[Kevin]

It looks like the consensus is new valve springs and a cam, 068/2801 or maybe slightly larger, should make for a good combo. Thank you for the input everyone.

[Jay S]

Originally Posted by Kevin

It looks like the consensus is new valve springs and a cam, 068/2801 or maybe slightly larger, should make for a good combo. Thank you for the input everyone.

I don’t know if that was a miss type, but a 2801 won’t work well with a 10:1 400 unless you plan to run some form of higher octane gas. 068 spreads the power out more than a 2801. Skip’s 2801 example is almost a point lower in compression than your 67 engine. Pump gas in a stock compression 67 400 would require a 2802 from that cam family.

[Kevin]

Thank you for the correction Jay!

Would Rhodes lifters have an effect on the cam selection for this engine?

[Jay S]

Originally Posted by Kevin

Thank you for the correction Jay!

Would Rhodes lifters have an effect on the cam selection for this engine?

Yes it would. Crower 60243 would be as small as you would want to run.